/*
 * Copyright 2009 Guenther Niess
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.kenai.jbosh;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.apache.http.HttpHost;
import org.apache.http.HttpVersion;
import org.apache.http.client.HttpClient;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.params.ConnManagerParams;
import org.apache.http.conn.params.ConnRoutePNames;
import org.apache.http.conn.scheme.PlainSocketFactory;
import org.apache.http.conn.scheme.Scheme;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.conn.ssl.SSLSocketFactory;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.impl.conn.tsccm.ThreadSafeClientConnManager;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpParams;
import org.apache.http.params.HttpProtocolParams;

/**
 * Implementation of the {@code HTTPSender} interface which uses the Apache
 * HttpClient API to send messages to the connection manager.
 */
final class ApacheHTTPSender implements HTTPSender {

	/**
	 * Lock used for internal synchronization.
	 */
	private final Lock lock = new ReentrantLock();

	/**
	 * Session configuration.
	 */
	private BOSHClientConfig cfg;

	/**
	 * HttpClient instance to use to communicate.
	 */
	private HttpClient httpClient;

	// /////////////////////////////////////////////////////////////////////////
	// Constructors:

	/**
	 * Prevent construction apart from our package.
	 */
	ApacheHTTPSender() {
		// Load Apache HTTP client class
		HttpClient.class.getName();
	}

	// /////////////////////////////////////////////////////////////////////////
	// HTTPSender interface methods:

	/**
	 * {@inheritDoc}
	 */
	public void init(final BOSHClientConfig session) {
		lock.lock();
		try {
			cfg = session;
			httpClient = initHttpClient(session);
		} finally {
			lock.unlock();
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public void destroy() {
		lock.lock();
		try {
			if (httpClient != null) {
				httpClient.getConnectionManager().shutdown();
			}
		} finally {
			cfg = null;
			httpClient = null;
			lock.unlock();
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public HTTPResponse send(final CMSessionParams params,
			final AbstractBody body) {
		HttpClient mClient;
		BOSHClientConfig mCfg;
		lock.lock();
		try {
			if (httpClient == null) {
				httpClient = initHttpClient(cfg);
			}
			mClient = httpClient;
			mCfg = cfg;
		} finally {
			lock.unlock();
		}
		return new ApacheHTTPResponse(mClient, mCfg, params, body);
	}

	// /////////////////////////////////////////////////////////////////////////
	// Package-private methods:

	private synchronized HttpClient initHttpClient(final BOSHClientConfig config) {
		// Create and initialize HTTP parameters
		HttpParams params = new BasicHttpParams();
		ConnManagerParams.setMaxTotalConnections(params, 100);
		HttpProtocolParams.setVersion(params, HttpVersion.HTTP_1_1);
		HttpProtocolParams.setUseExpectContinue(params, false);
		if (config != null && config.getProxyHost() != null
				&& config.getProxyPort() != 0) {
			HttpHost proxy = new HttpHost(config.getProxyHost(),
					config.getProxyPort());
			params.setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);
		}

		// Create and initialize scheme registry
		SchemeRegistry schemeRegistry = new SchemeRegistry();
		schemeRegistry.register(new Scheme("http", PlainSocketFactory
				.getSocketFactory(), 80));
		SSLSocketFactory sslFactory = SSLSocketFactory.getSocketFactory();
		sslFactory
				.setHostnameVerifier(SSLSocketFactory.ALLOW_ALL_HOSTNAME_VERIFIER);
		schemeRegistry.register(new Scheme("https", sslFactory, 443));

		// Create an HttpClient with the ThreadSafeClientConnManager.
		// This connection manager must be used if more than one thread will
		// be using the HttpClient.
		ClientConnectionManager cm = new ThreadSafeClientConnManager(params,
				schemeRegistry);
		return new DefaultHttpClient(cm, params);
	}
}
